The present invention relates generally to apparatus for controlling tension in a traveling yarn or the like and, more particularly, to such a yarn tension control apparatus adapted for disposition in a textile draw-warping system intermediate a drawing apparatus and a warp beaming machine.
In virtually all systems involving the handling of yarn and similar strand-like materials, it is a characteristic requirement that the tension conditions in the material be controlled in order to best insure high quality results. This is particularly true in the handling of traveling yarns in typical textile manufacturing systems. Conventionally, the control of yarn tension in such operations has been commercially achieved by imposing an essentially fixed restraint, drag or load exerting a frictional force on the advancing strand. Disadvantageously, tension control devices operating in this manner provide only moderate effectiveness in maintaining yarn tension within a desirable range and are essentially effective primarily in merely maintaining a minimum tension in the yarn. Specifically, the restraint imposed by such devices on the traveling yarn is effective to compensate for tension losses by maintaining a minimum restraint against yarn travel. However, such devices effectively magnify tension increases in the yarn, rather than compensating for and offsetting such fluctuations, which may sometimes result in yarn breakage.
In textile draw-warping systems, a plurality of continuous filaments of synthetic polymeric materials of the type suitable for use as textile yarns are fed generally in side-by-side relation to a drawing apparatus wherein the filaments are drawn longitudinally and heat set to align and order the molecular and crystalline structure of the filaments to a desired degree, following which the plural filaments are guided to a warp-beaming machine by which the filaments are wound side-by-side onto a spool or beam in preparation for subsequent feeding of the yarns to a weaving, warp-knitting or similar fabric-forming apparatus. As in any other warp-preparation operation within the textile industry, it is important that the individual filamentary yarns be wound onto the warp beam by the beaming machine at a substantially uniform tension. For this purpose, it is conventional to incorporate a tensioning mechanism of the above-described type in advance of the warp beaming machine for imposing a frictional drag on the drawn filamentary yarns as they enter the beaming machine.
Another consideration in the design of textile draw-warping systems is the periodic necessity of interrupting the normally continuous draw-warping operation, for example, when any one of the traveling filaments breaks or for other reasons experiences a significant loss in tension activating a stop motion arrangement of the draw-warping equipment. For economic reasons, it is desirable to operate draw-warping systems at an operating speed, i.e. the traveling speed of the filaments, as high as practicably possible. Thus, whenever stoppage of the draw-warping system is necessary, it is not practical or possible to effect immediate stoppage of the traveling filament movement. Accordingly, draw-warping systems are conventionally designed with the warp beaming machine spaced a sufficient distance from the stop motion arrangement in relation to the normal filament traveling speed and the rate at which the system is capable of braking to a complete stop so as to insure that system stoppages are completed in the event of a filament breakage before the broken filament or filaments are taken up by the warp beaming machine. As will be understood, this manner of construction substantially increases the overall length of draw-warping equipment which is considered highly disadvantageous by users because of the substantial floor space required.